综合布线系统设计-毕业设计-外文翻译(共18页).doc

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1、精选优质文档-倾情为你奉上附件1 外文资料翻译译文：综合布线的未来JHMI(约翰斯霍普金斯医学研究所)前提的分配计划将与由ATT的前提分配制度和国际标准组织的综合业务数字网指定的标准相一致。这包括护墙板的水平布线分布，和语音/数据配线间交叉连接设备的模块化。从靠近长城站的语音/数据布线建议线路部署小于230英尺。水平分布电线和墙面板ATT的“D”类非屏蔽双绞线应被使用。每个语音/数据长城站将达到四对“D”类电缆的要求。每4对 D 类线缆将被汇聚在一个标准RJ45 (8位)信息插座，以便使每个墙面板需要安置四个RJ-45信息插座。垂直配电线路和语音/数据配线间配线间一般都部署在每一层楼。因为某些

2、更旧的大厦座位有限，根据具体情况必须对原有房屋进行评估。对于新楼宇，每个小房间应该至少可以容纳两个标准19机架。其中每项主要的前提计划推荐在19机架上安装电子设备。较大的电子元器件，需要全帧计算机机架。这些机架将支持ISDN（综合业务数字网），以太网和令牌环组件。此外,交叉连接面板将需要电话线路、终端线路，以太网连接和未来的令牌环。交叉连接的两个小组将需要单独设置。数据线将端接于其中一组面板，而语音线则在另一块。由于两个分开的组织维护同一组相同的线缆，这将分离作用并且使混乱减到最小。数据线将安装在适当的机架式数据硬件（如3274控制器，以太网桥箱等），而语音线（如可能）则将安装到机架式语音硬件

3、。但是，如果需求发生变化，基本接线厂商将能够支持，无论是语音或数据的技术。模块化的交叉连接设备提供长期的维护和可重构性更容易。有许多可用的配置，可从如Mod-Tap（国防部抽头）、Nevada Western（耐威）和奥创利的第三方资源获得。在这一点上，然而，很有可能是JHMI要和AT&T使用同一个解决方案。每栋建筑到互连的地下室至少两根粗缆以太网段(贝尔登9880或同等材质)才能贯穿。线圈应该留待日后安装在每个楼层。以太网电缆必须有随时可用的访问（即不是在管道运行），以确保日后使用。在每幢楼至少将安装一根62.5/125微米光纤冒口，以便为将来的数据通信使用。充分批量的语音通信电缆冒口应该被

4、部署，以满足当前和预计的需求。再次，现有建筑物的布线将需要考虑到可行性评估。在许多建筑物的地下室配线间将作为一个中间配线架回到主配线架。建筑物间互连可能会依靠光缆，尤其可以增加数据通信网络的带宽。结构化布线系统(SCS）最简单地说就是，在安装时基于遵循EIA / TIA 568规范定义的标准，网络规划和商业建筑布线方法。本标准的目的是指定一个通用的、能够支持多产品，多厂商环境的商业建筑物电信布线系统。它还提供了一些可以用来为商业企业设计通讯产品的信息。在EIA/TIA-568标准包括EIA/TIA-568-B.1一般要求，EIA/TIA-568-B.2铜布线要求，EIA/TIA-568-B.3

5、光纤布线要求。工业思考还有什么能够改变与结构化布线系统相关的工业环境吗?其实很少。包括安装要求和测试要求适用标准都是一样的。并且，如果您安装的一切符合美国电器制造商协会额定的范围内，那么什么都不需要变的。不过，如果你想从机箱外面进入网络，那么有一个新的连接方式称为工业RJ45。这些规范由EIA/TIA和ODV（开放是数字视频）开发并且是几乎已经完成。许多IT经理感到不太确定应该跟随哪些新的技术。这部分归结于制造商的可观的营销炒作。规范体也需要时间批准6类线，因此导致在产业之内的不确定性。我们将提出一种战略和结构化布线，这将是当今标准的最具成本效益的解决方案。我们将会研究：未来网络设计的影响；什

6、么将会有可能在技术上实现；在布线基础设施中我们需要什么。总结高规格的铜布线在数据网络（6或7类）中所提供的好处很可能是有限的，短暂的。为了避免今后严重的网络中断，节省昂贵的返工，“光纤到桌面”是值得认真考虑的新项目。这也可能是对您竞争性冲击的企业重要决定。我们现在应该做什么，可以保证我们新的网络设施不会成为未来(或许一点也不遥远)的传统网络。网络的单调上升1980年以来的数据传输速率，当网络速度被由（clunkety -弹响电传打字机）机械转速机制决定时，网络已经看到了数据传输速率的单调上升。在过去，上升趋势始终密切遵循“摩尔定律”，但最近，它提供的证据表明速度加速快于由定律预测的。一吉比特数

7、据速率现在是可利用的，然而到2005年它预计达到10吉比特。在任何建筑物分布中，“垂直”网络运行约80的流量。这种建筑物局部区域网络（LAN）是关键业务的一部分，但是幸运地，它是相对地容易对它做变动的。很多时候，这个网络的一部分，是用光纤实现的。有一段时间，通过光纤提供的带宽，被认为是无限的，但事实并非这样。例如，在1吉比特速度时，当使用流行的62.5/125m多模光纤还有约220米长度的限制。当使用50/125m光纤时，可以增加至约500米。更远的距离意味着单模光纤的使用。对大厦垂直LAN的所有变动，可能通常与现有的网络服务平行实施，因此到桌面的服务的中断可以被保留到极小值。正因为如此，由于

8、网络服务的中断对组织成本的影响，可以保持小规模。水平局域网当考虑建筑物内的“水平”分布时，正如“摩尔定律”预测的那样，我们看到了在数据传输速率上同样的增长，显示出了近期的加速趋势，但还是落后垂直数据速率5年。因此，我们希望到2000年能达到1吉比特数据速率和2007年达到10吉比特数据传输速率。事实上， 1吉比特网络接口卡(NIC)现在已经开始进行传输；我们开始接受在桌面吉比特网络的需求之前，它只是时间问题。高带宽或关键比特率应用例如VOIP，视频流，视频会议和计算机辅助设计(CAD)，正逐渐变得普遍。不同于建筑物的垂直局域网,水平网络的升级是非常昂贵。施工总是意味着严重扰乱了大楼居住者的正常

9、工作，因此这类活动通常是，有主要的结构性翻新工程时才进行的。在墙壁、地板或天花板上或下面，必须形成空中缆绳。安装程序必须确保结果并不难看，但也不可避免地破坏了必须有线缆通过的房间的美化价值。提供电源、音频/数据线缆所采取的处理必须控制在足够并且美观程度上。这一切都意味着费用。承包商的成本高。 严格地说正是因为这些高费用，于是开发了非屏蔽双铰线(UTP)以太网。这将允许在建筑物内使用现有的、低等级的3类电话线缆。为改善这种大众媒体的带宽能力已付出了艰苦的努力。但是，一旦确立，随着这个系统的经济改善，只得通过重新设计的电缆，这导致在管道中5类，5e类、6类和7类线缆的生产。这些改进已促使10兆，1

10、00兆和1吉UTP以太网的发展。事实上,有人说，在铁丝网上，你接收和发送数据的速率在误差率接受的范围内可以达到吉比特位/秒。这只是一个你愿意为编码器和解码器支付多少的问题！铜线缆的限制在非常高的数据速率对UTP铜缆布线的使用有内在的局限性。它们是：金属导体磁化率的属性的温度波动。由于从缆绳的辐射，越来越多的信号强度以高数据速率的形式损耗。相对较大的外部串扰影响着弱信号,尤其是在线缆末端附近。数据线缆分享邻近的包含总线布线的电缆这是极为重要的。在同一线缆中导线对之间的增强信号耦合（串音）。这种情况在它连接硬件的缆绳的末端时被恶化。在连接器上,相对高功率的信号被发射进非常靠近到接收的电缆,沿着电缆

11、长度辐射损失已经开始减弱。这些薄弱接收信号可以从发射器耦合器淹没不需要的信号。为了克服这些困难，在收发器的硬件设计方面必须投入更多。这些项目的成本将随着带宽的增加而增加。现在已经开始开发6类线缆，以便解决其中一些问题，但是，目前，还没有批准任何标准。除了这些“流动的”方面的铜解决方案,还应该牢记影响他们的选择的其他因素。或许最重要的是将考虑6类线缆提供的相当低带宽的改进。网络带宽不断上升的预期将很快超过它，通过把可提供的2.5 Gbs- 1的理论投入使用。这个暂缓的过程很有可能是短的。大约有其互操作性和对现有设施的向后兼容的进一步担忧。7类线缆目前仍处于研发阶段，但在许多业内专家来看，研发是值

12、得的。7类线的最坏预言情况是达到10吉比特速度后暗示着线缆长度限制为大约25m。这必将是一个非常残酷的限制。所有的改善将是在牺牲更加昂贵的收发器的基础上。不管结果如何，在更高的数据速率时的距离限制，对于UTP布线来说是很麻烦的。 7类布线，然后，必须至少有一个光纤解决方案？光学技术从另一方面来看，光学技术已经是先进的。扩展带宽多模光纤和VCSEL激光器的发展已经促使光学技术改进。普通多模光纤的折射率分布并不遵循跨越核心直径的理想抛物的变化。这些光纤在位于光纤的轴处有一个不连续的小指标,以防止近轴射线被及时有效的传达。这些是受到最少的色散影响的射线，然而它却是允许使用高信号率的低等分散。扩展带宽

13、多模光纤，已经制定了一个改进的折射率分布。他们又提高了在多模光纤上可传播的吉比特以太网的距离到大约1km。VCSEL激光器有沿光纤中心近轴射线发射的能力，它是使用扩展带宽光纤的理想助手。传统上，铜网络比他们的光学相应物便宜，但是，当数据速率增加时，安装这些媒介的费用将聚合。这可能发生在2.5 Gbs速率。未来显然,对未来的所有需求预测是困难重重的,我们必须依赖于过去的经验。当处理水平网络时，错误判断将带来昂贵而持久的后果。但通常只有一个得到正确的机会，因为水平布线的寿命是10年或更多点。通过对比的方式，PC机的寿命约为2 - 3年，而以太交换机3 - 5年。鉴于此,正确的选择水平布线是至关重要

14、的。对于10Mbs工作，铜3类电缆很足够了。对于100Mbs工作，铜5类电缆是必需的。对于1 Gbs工作，铜5e类电缆是必需的。对于10 Gbs的工作，延长工作50/125m的光纤电缆是必需的。如果，作为趋向建议，我们也许期待在布线的寿命之内10Gbs的操作，然而，事实上，水平布线是昂贵的改变，我们应该尽我们所能设法使当前的装置作为所谓“面向未来的”。因为改进的铜缆布线提供的解决方案很可能是短暂的，也很可能和光纤一样昂贵，所以我们需要在所有的新工作考虑提供光纤。如果因为目前的成本问题，在任何给定的项目并不实际安装光纤，但至少，在布线内容中应该预留光纤的空间，以适应未来的应用。一种实现这一没有铺

15、设任何实际的光纤的方法就是是使用“气吹光纤”导管。这是一种藉以沿着传统布线的输送管道安装光纤的技术。他们随后可能会投入使用，通过使用压缩空气将光纤吹入预装管道下到目的地。这具有下列优点：对装修有最小的干扰；对大厦的员工正常工作模式有最小的干扰。当在零碎的基础上且和现有的线路同行需要或预算许可时，光纤可以提供额外的带宽。它允许将开支推迟。气吹光纤是“原始”（直径约0.1毫米）的光纤。它是由预安装管道保护的免受损坏。它比传统的由熟悉的塑料护套包装的光纤电缆更便宜。如果环境改变或发生损坏，光纤的等级可以被改变。老化的光纤能够快速方便地回收,并且被不同的光纤取代。输送管道是小的，并且可以通过传统的线缆

16、包含进行运载。损坏的管道可以切去进行修理，并且损坏的部分也可以用新的管替换它。因为光纤具有成熟的优势技术,大大优于电噪声免疫、本质电气安全,优越的带宽能力,数据高度安全性，通过长距离携带数据的能力允许在“主干”的拓扑结构中使用，所以它的用途或潜在的用途应该在所有新线缆施工时认真被考虑。如果历史告诉我们什么，那就是没有任何解决方案是“面向未来的”。外文原文：The Future of Structured Cabling The JHMI Premise Distribution Plan will be consistent with standards specified by the AT

17、&T Premise Distribution System and the International Standards Organizations Integrated Services Digital Network. This includes wallplates, wire for the horizontal distribution and the voice/data wiring closet modular cross connection equipment.It is recommended that wire runs be less than 230 feet

18、from the voice/data wiring closet to the wall station.Horizontal Distribution Wire & Wallplates AT&T type D unshielded twisted pairs shall be used. Each voice/data wall station will receive four type D cables. Each 4-pair D cable will be terminated in an standard RJ45 (8-position) jack so that each

19、wallplate will need to house four RJ-45 jacks.Vertical Distribution Wire & Voice/Data Wiring Closets The wiring closets are generally located on each floor of a building.Existing buildings must be evaluated on a case-by-case basis since some of the older buildings have limited space. For new buildin

20、gs, each closet should be large enough to accommodate a minimum of two standard 19 computer racks. Each of the major premiseplans recommends mounting electronics in 19 racks. The larger electronic components will require full frame computer racks. These racks will support the ISDN, Ethernet and Toke

21、n Ring components. In addition, cross connection panels will be required for the telephone wiring, terminal wiring, Ethernet connections and future Token Ring. Two separate sets of cross connection panels will be required. The data wires will terminate in one set of panels and the voice wires in ano

22、ther.This will segregate functions and minimize confusiondue to two separate organizations maintaining the same set of wires.The data wires will be patched into the appropriate rack-mounted data hardware (i.e. 3274 controllers, Ethernet Bridge boxes, etc.) and the voice wires will be patched into th

23、e rack-mounted voice hardware (where possible). However if needs change, the base wiring plant will be able to support either the voice or the data technology. Modular cross connection equipment provides easier long-termmaintenance and reconfigurability. There are many configurationsavailable from t

24、hird party sources such as Mod-Tap, Nevada Western and Ortronics. At this point, however, it is most likely that JHMI will go with an AT&T solution. A minimum of two ThickWire Ethernet segments (Belden 9880 or equivalent) will be run through each building to the interconnecting basements. Loops shou

25、ld be left on each floor for future installations.Ethernet cable must have readily available access (i.e. not run in conduit) to insure future use. A minimum of one 62.5/125 micron fiber riser will be installed in each building riser for future data communications use. Sufficient bulk voice communic

26、ations riser cable should be run to meet the current and projected requirements. Again, the wiring of existing buildings will need to be evaluated with feasibility in mind. In many buildings the basement wiring closet will act as an intermediate distribution frame back to the main wiring frame. Inte

27、r-building linkswill probably be run using fiber optic cable especially to increase the bandwidth of the data communications networks.A Structured Cabling System (SCS) most simply stated is based on following a standard methodology defined by EIA/TIA 568 specifications when planning and installing n

28、etwork cabling for commercial buildings. The purpose of this standard is to specify a generic telecommunications cabling system for commercial buildings that will support a multi-product, multi-vendor environment. It also provides information that may be used for the design of telecommunications pro

29、ducts for commercial enterprises.The EIA/TIA-568 standard includes EIA/TIA-568-B.1 General Requirements,EIA/TIA-568-B.2 Copper Cabling Requirements, EIA/TIA-568-B.3 Fiber Cabling Requirements.Industrial ConsiderationsSo what changes for the industrial environment related to the SCS? Actually very li

30、ttle. All the same standards apply including installation requirements and test requirements. And if you mount everything inside NEMA rated enclosures then nothing changes at all. However if you want to plug into the network from outside the enclosure there is a new connector style available called

31、Industrial RJ45. The specifications are being developed by EIA/TIA and ODV and are nearly complete.Many IT managers are unsure of which new technologies to follow. This is partly due to the considerable marketing hype from the manufacturers. The standards bodies are also taking time to ratify catego

32、ry 6 and this is causing uncertainty within the industry.We will be presenting a strategy and method for structured cabling that will be the most cost effective solution for todays standards.We will examine:-The Implications for future network design，What is likely to be technically achieved，What wi

33、ll we require in the cabling infrastructure.SummaryThe advantages offered by high specification copper cabling (category 6 or 7) in data networks are likely to be limited and short lived.In order to avoid serious network disruptions in the future and save costly reworking, optical fibre to the deskt

34、op deserves serious consideration for new projects. This is also a business critical decision which could impact on your competitiveness. We should do what we can now to ensure our new network installations do not become the legacy networks of the (perhaps none too distant) future.Monotonous Rise in

35、 Network Data Rates since the 1980s when network speeds were dictated by the rotor speed of mechanical mechanisms (clunkety-clunk teletypes), the networks have seen a monotonous rise in data rates. The rise has followed Moores Law closely in the past but recently, it has shown evidence of an acceler

36、ation faster than that predicted by the law. One-gigabit data rates are available now and 10-gigabit rates are predicted by 2005.Vertical LANIn any building distribution, the vertical network carries about 80% of the traffic. This part of a building local area network (LAN) is business critical but

37、fortunately, it is relatively easy to make changes to it. Quite often, this part of the network is realised as optical fibre. At one time, the bandwidth offered by optical fibre was regarded as unlimited but that is not the case now. For example, at 1-gigabit rates, there is a length limit of about

38、220m when using popular 62.5/125m multi-mode fibre. This can be increased to about 500m when using 50/125m fibre. Greater distances imply the use of monomode fibre. Any changes to the building vertical LAN can usually be made in parallel with the existing network services so disruption of the servic

39、e to the desktop can be kept to a minimum. Because of this, costs to the organisation due to interruption of network service can be kept small.Horizontal LANWhen considering the horizontal distribution within a building, we see the same increase in data rates as predicted by Moores Law, showing the

40、recent accelerating trend but lagging the vertical data rates by 5 years.So, we would expect 1-gigabit data rates by year 2000 and 10-gigabit data rates by year 2007. Indeed, 1-gigabit network interface cards (NIC) are being shipped now; it is just a matter of time before we start receiving demands

41、for gigabit networking at the desktop. High bandwidth/critical bit rate applications such as VOIP, video streaming, video conferencing and computer aided design (CAD), are becoming common. Unlike the buildings vertical LAN, the horizontal network is very costly to upgrade. Installations always mean

42、serious disruption to normal work for a buildings occupants, so this sort of activity is normally undertaken when there is a major refurbishment of the fabric. Cableways have to be formed in, on or under walls, floors and ceilings. The installers have to ensure that results are not unsightly but ine

43、vitably there is damage to the amenity value of the rooms through which cables have to pass. Care has to be taken to provide adequate and presentable cable containment for both power and voice/data cables. This all means expense. The cost of ownership is high. It was precisely because of these high

44、costs that unshielded twisted pair (UTP) ethernet was developed. This permitted the use of existing, low grade, category 3 telephone cabling within buildings. Strenuous efforts have been made to improve the bandwidth capabilities of this popular medium. However, once firmly established, economic imp

45、rovements to this system could be made only by redesign of the cable, leading to the production of category 5, 5e and 6 cables with category 7 in the pipeline. These improvements have enabled the development of 10-megabit, 100-megabit and 1-gigabit ethernet over UTP. Indeed, it has been said that yo

46、u can transmit and receive data at gigabit per second rates with acceptable error rates over barbed wire. Its only a matter of how much you are willing to pay for the encoder and decoder!Limitations of Copper CablingThere are intrinsic limitations to the use of UTP copper cabling at very high data r

47、ates. These are:The susceptibility of the metallic conductors properties to fluctuations in temperature.The increasing loss of signal strength at high data rates due to its radiation from the cable.The relatively large effects of external interference on weak signals, particularly near the ends of t

48、he cable. This is especially important where data cables share adjacent cable containment with mains wiring.The increased signal coupling between pairs of conductors in the same cable (crosstalk).This situation is exacerbated at the ends of the cable where it is attached to the hardware. At the connector, relatively high power transmit signals are launched into the cable in very close proximity to the receive signals that have already been attenuated by radiation loss along the cables length. These weak receive signals can be swamped by the unwanted coupled signal from the transmi